Serrated Tussock

Nassella trichotomaFamily: Poaceae

Growth Habit: Young plants are erect and densely tufted with tightly inrolled leaves. As the plant grows to maturity, the later leaves become longer, the tips turning to brownish green or, in winter, a bleached straw colour. Leaves at all growth stages feel rough or serrated if the finger and thumb are drawn down the blade. Grows to 50 cm in height and can occupy 75 sq cm.

Type of Plant: Perennial, tussock forming grass.

Flowers: Flower stalks usually appear in spring (although they can appear earlier or later, depending on the availability of water). The flowering heads are carried on slender stalks slightly longer than the leaves. Each flower head is an open, branched panicle, the primary branches in pairs, slender and drooping. A tussock in full flower in early summer presents a distinctly purple appearance due to the large number of purple florets.

Fruit/Seed: Each floret produces one seed, about 2 mm long, pale straw coloured, with a tuft of short hairs at the base and a long, slender, twisted awn from the tip.

Dispersal: When the seeds are ripe the flower stalk becomes very brittle, strong wind breaks it off and the whole seed head is blown along until it lodges against some obstacle. As the seed head dries out, the seeds are released and fall to the ground to begin a new colony.

In Tasmania human activities have been responsible for introducing and spreading the weed. The tuft of basal hair and the awn of the seed allows it to catch on the fleece of sheep. It may also be picked up in mud, on the hooves of livestock, on cultivating implements, in vehicle tyres or on firewood. Quarantine measures now in force are aimed at preventing its spread by any of the above means.

Distribution: All known serrated tussock infestations in Tasmania are in the far southeast.

Status: Serrated tussock is declared a Noxious weed under the Noxious Weeds Act 1964 in Tasmania and is therefore subject to eradication, with all affected land placed under quarantine.

Weed Impact:

Dense infestations may completely swamp out all other pasture components, rendering large areas incapable of supporting livestock.

Grows well in poor soil and survives better than most other grass species.

Once established, it can survive fire, drought and frost.

Control Methods:

Physical removal, e.g. grubbing with a mattock, is the most satisfactory method where this is practicable. Care must be taken to ensure seed is not spread during removal.

Glyphosate and flupropanate (Fenrock) herbicides are useful in some situations. For specific recommendations on herbicides for serrated tussock control, contact the Department of Primary Industry and Fisheries for a copy of the Serrated Tussock Service Sheet or your local rural merchandiser. N.B. The herbicides mentioned on this documents may not necessarily be registered for use on the plant referred to.